2000 GMC Yukon Stuck In 4 Wheel High

2000 GMC Yukon-4×4 is stuck in 4hi. service 4wd light on dash is on. i changed the dash switch, same problem. i pull off the transfer case actuator and hit switch, it makes a noise and the front diff act makes noise too. the transfer case actuator does not turn though. is it supposed to?

Yes it should move, you most likely have a bad encoder motor.

There is a sticker on the side of it that says-warning actuator motor will cause permanent damage f used with out transfer case. Does that mean when i have it out hanging there to see the rotation, i damaged it?

You do NOT want to activate it while it is removed from the transfer case.

It would be best to get the truck scanned to see what trouble codes are stored in the transfer case control module. That would help with diagnosis and tell you if you have a bad encoder motor.

Will a regular OBD2 scanner work?

Only if it can communicate with other modules, regular code scanners for the general public usually only pull engine codes.

How do i know it is not the front diff act instead? is there a way to diagnose? is the brown wire supposed to have 12v?

It cannot be just the front actuator, that does NOT control high or low speed, just the transfer case does that, so the problem has to lie in there.

Is there a way to tell if it is the sensor that is in the actuator?

The encoder motor is not serviceable, you’d have to replace the entire actuator, not just the sensor.

I thought there were 2xtox20 and 2x torx15 screws on it and if i take them off the sensor is inside on the shaft? you can buy the sensor separate too?

You can get the sensor separately. But If the encoder motor is bad, you have to REPLACE it as ONE part.

Ok. thank you for the advice. is there something I could be missing? The encoder motor does make a turning sound but the rectangle in the hole does not turn? Almost like a gear grinding turning sound.

Then it is bad, or internally broken. I’d recommend replacing it.

Thank you. how do i send a tip or payment for the advice?

I will send you a link if you wish to donate / tip. Thank you for your consideration.


2000 GMC Yukon

Service 4wd light came on. changed out dash switch, and then the encoder motor. light still on. thoughts?

Mechanic JK:
Does the 4wd function correctly? Any other warning lights on the dash?

It feels like its in 4hi. i have not put it up on jack stands to verify though.

Well, you have replaced the 2 most common items for this condition. Without a scanner and some circuit testing, the other most common thing is a bad transfer case control module.

Where is that located on the transfer case? Could it be the front diff actuator? If i push the buttons to change 4hi to 2hi it doesn’t change lights flash and then all go out-service 4wd comes up.

The control module is located behind the dash. Different locations for different years. I would a few minutes to check the location for you truck. Yes, it could be the front actuator, but you would be just guessing without doing some testing. There is most likely a trouble code stored in the control module. A scanner would be needed to check that.

My obd2 equis doesn’t show a code? do i need the $10k dealer scanner?

Does your scanner communicate with the transfer case module?

I am not sure. i would say no because it did not show any codes.

Give me a few moments to look at something…

Is there a way to count the flashes of a light or something? gone are the days of the paperclip as a jumper i suppose.

Yes, the codes need to get scanned. There are a few codes that point straight to a faulty module. But any component can also set a code. Dealer scanner or local garage with good equipment is really needed hear. If it were a bad module, it would need to be programmed by the dealer scanner anyway.

Great thank you !


1999 GMC Truck

The speedometer is not working just replaced the battery the needle just stays stuck on the right side.

Sounds like you had an electrical glitch which shorted the cluster. Does the needle move at all?


Those particular instrument clusters were known to have problems with the speedometer needles sticking. You will probably need a replacement cluster.

Sorry but what is a cluster.

The cluster is where all the gauges are. The speedometer, tach, temperature, volts, etc…That is called a cluster. It is one unit and would need to be replaced as a whole unit. It would then need to be programmed.

Thank you very much i will take it to the mechanic.

You are welcome, glad to help!

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